1. Field of the Invention
The present invention relates to a flexible organic crystal that is not broken, because the crystal is deformed in accordance with exerted force when the force such as bending force is externally exerted, and more particularly to an organic crystal used as a channel material of a flexible electronic device.
2. Description of the Related Art
A flexible electronic device such as a flexible organic field effect transistor (FET: Field Effect Transistor) has been progressively developed by using the flexibility of an organic material.
The flexible electronic device is deformed in accordance with exerted force when the force such as the bending force is externally exerted. Accordingly, since an electronic equipment in which the flexible electronic device is incorporated can be folded and carried, the electronic equipment is advantageously easily portable and hardly broken even when the force is exerted thereon. (see Japanese Patent Application Laid-Open No. 2003-119255).
There is a large difference in work function between the organic material and an inorganic material. Thus, when the transistor is formed, if the organic material is used for a channel layer and the inorganic material is used for an electrode material, a barrier is liable to be generated between the organic material and the inorganic material so that a carrier is hardly moved. Accordingly, when the flexible transistor is manufactured, the organic material is preferably used for a wiring material to make the carrier movable so that the barrier is decreased between the electrode and the channel.
Further, the channel layer is ordinarily formed with a polycrystalline organic material having a high flexibility and an electric conductivity. The channel layer formed with the polycrystalline organic material has the mobility of the carrier of about 1 cm2/Vs which is not satisfactory speed. As a cause that the mobility of the carrier is low, the generation of the diffusion of the carrier on a crystal interface is considered. As a method for suppressing the diffusion of the carrier generated on the crystal interface to improve the mobility of the carrier, a method for forming the channel layer with a single crystal organic material is exemplified.
However, the single crystal organic material is ordinarily low in its flexibility and brittle for a deformation. Accordingly, since a transistor having the channel layer formed with the single crystal organic material is not deformed in accordance with exerted formed when the force is externally exerted, the transistor is hardly used as a flexible transistor.